We perform the analysis of elastic scattering $pp$ and $\overline{p}p$ data at low momentum transfer $|t|<0.1{\mathrm{GeV}}^2$ within large collider energy interval $\sqrt{s}=50\mathrm{GeV}–13\mathrm{TeV}$ in order to evaluate quantitatively the possible Odderon contribution. We use the two-channel eikonal model, which naturally accounts for the screening of the Odderon amplitude by $C$-even (Pomeron) exchanges.

We present GFlaT, a new algorithm that uses a graph-neural-network to determine the flavor of neutral $B$ mesons produced in $\mathrm{\Upsilon }(4S)$ decays. It improves previous algorithms by using the information from all charged final-state particles and the relations between them. We evaluate its performance using $B$ decays to flavor-specific hadronic final states reconstructed in a $362{\mathrm{fb}}^{-1}$ sample of electron-positron collisions collected at the $\mathrm{\Upsilon }(4S)$ resonance with the Belle II detector at the SuperKEKB collider. We achieve an effective tagging efficiency of $(37.40\pm 0.43\pm 0.36\%)$, where the first uncertainty is statistical and the second systematic, which is 18% better than the previous Belle II algorithm. Demonstrating the algorithm, we use $B^0\to J/\psi K_{\mathrm{S}}^0$ decays to measure the mixing-induced and direct $CP$ violation parameters, $S=(0.724\pm 0.035\pm 0.009)$ and $C=(-0.035\pm 0.026\pm 0.029)$.

Predicting the properties of the matter ejected during and after a neutron star merger is crucial to our ability to use electromagnetic observations of these mergers to constrain the masses of the neutron stars, the equation of state of dense matter, and the role of neutron star mergers in the enrichment of the Universe in heavy elements. Our ability to reliably provide such predictions is however limited by a broad range of factors, including the finite resolution of numerical simulations, their treatment of magnetic fields, neutrinos, and neutrino-matter interactions, and the approximate modeling of the equation of state of dense matter. To disentangle some of these uncertainties, in this manuscript we focus narrowly on the impact that two small variations in the setup of numerical simulations can have on the matter ejected during the merger. Specifically, we perform 4 simulations: one at higher residual eccentricity ($e\sim 0.01$), two with reduced eccentricity ($e\sim 0.003–0.004$), and slightly different equation of state implementations, and a fourth at higher resolution to estimate numerical errors. We perform these simulations for a single physical configuration, a $1.3M_{\odot }-1.4M_{\odot }$ binary neutron star system using the SFHo equation of state, ignoring magnetic fields and neutrino effects. We find that a residual eccentricity $e\sim 0.01$, as measured $\sim 4–6$ orbits before merger, causes $O(25–30\%)$ relative changes in the amount of ejected mass. These differences in mass ejection appear mainly due to changes in the amount of matter ejected as a result of core bounces during merger. We note that $O(1\%)$ residual eccentricities have regularly been used in binary neutron star merger simulations as proxy for circular binaries, potentially creating an additional source of error in predictions for the mass of the dynamical ejecta. On the other hand, we find that simulations performed with slightly different implementations of the same equation of state are consistent within estimated numerical errors.

Light-ring bifurcations that can occur for prolate non-Kerr compact objects can leave an indelible signature on supermassive black hole shadows as a fractal sequence of eyebrow-like formations. These fractal features are the result of two properties of these spacetimes. The first is that they allow for multiple escapes for the photons (throats in the effective potential of photon geodesic motion). The second is that photon geodesics can resonate between different generalized light rings related to the escapes, called fundamental photon orbits, that lead photons to alternate between the different exits—toward either the compact object or infinity. The resulting fractal structures of the shadow seem to be a generic feature of prolate non-Kerr objects that may be observable in (accretion disk)-illuminated compact objects, especially along equatorial lines of sight, but the best orientation depends on the specific parameters. Such fractal features, if observed in the shadows of singular supermassive black holes at the centers of galaxies, would be smoking-gun signals of non-Kerr compact objects.

We analyze perturbations of self-interacting, scalar field dark matter that contains modes in both a coherent condensate state and an incoherent particlelike state. Starting from the coupled equations for the condensate, the particles’ phase-space distribution, and their mutual gravitational potential, first derived from first principles in earlier work by the authors, we derive a hydrodynamic limit of two coupled fluids and study their linearized density perturbations in an expanding universe, also including particle pressure under an assumption for an equation of state consistent with the dynamical equations. We find that away from the condensate-only or particle-only limits, and for certain ranges of the parameters, such self-interacting mixtures can significantly enhance the density power spectrum above the standard linear $\mathrm{\Lambda }\mathrm{CDM}$ value at localized wave numbers, even pushing structure formation into the nonlinear regime earlier than expected in $\mathrm{\Lambda }\mathrm{CDM}$ for these scales. We also note that such mixtures can lead to degeneracies between models with different boson masses and self-coupling strengths, in particular, between self-coupled models and noncoupled fuzzy dark matter made up of heavier bosons. These findings open up the possibility of a richer phenomenology in scalar field dark matter models and could further inform efforts to place observational limits on their parameters.

Recent analysis of quantum cosmology has focused on the Lorentzian path integral formulations of both the no-boundary and tunneling proposals. However, it has been criticized that the wave function for linearized perturbations around a homogeneous and isotropic background leads to an inverse Gaussian distribution. This results in divergent correlation functions and cosmological inconsistencies. In this paper we explore these perturbation problems in Lorentzian quantum cosmology, focusing in particular on the quantum creation of the closed, flat, and open universe from no spacetime and the beginning of primordial inflation. We show that most quantum cosmological scenarios have serious perturbation problems. We also study the effects of trans-Planckian physics on quantum cosmology, using the generalized Corley-Jacobson dispersion as a case study of modified dispersion relations. Our findings indicate that resolving perturbation problems in Lorentzian quantum cosmology with modified dispersion relations remains a challenge. However, the perturbations can be Gaussian in the quantum creation of the flat or open universe within the confines of the saddle-point approximation and the generalized Corley-Jacobson dispersion.

Gravitational waves from binary mergers at cosmological distances will experience weak lensing by large scale structure. This causes a (de)magnification, $\mu$, of the wave amplitude, and a completely degenerate modification to the inferred luminosity distance $d_L$. The customary method to address this is to increase the uncertainty on $d_L$ according to the dispersion of the magnification distribution at the source redshift, ${\sigma }_{\mu }(z)$. But this term is dependent on the cosmological parameters that are being constrained by gravitational wave “standard sirens,” such as the Hubble parameter $H_0$, and the matter density fraction ${\mathrm{\Omega }}_{\mathrm{m}}$. The dispersion ${\sigma }_{\mu }(z)$ is also sensitive to the resolution of the simulation used for its calculation. Tension in the measured value of $H_0$ from independent datasets, and the present use of weak-lensing fitting functions calibrated using outdated cosmological simulations, suggest ${\sigma }_{\mu }(z)$ could be underestimated. This motivates an investigation into the consequences of mischaracterizing ${\sigma }_{\mu }(z)$. We consider two classes of standard siren, supermassive black hole binary and binary neutron star mergers. Underestimating $H_0$ and ${\mathrm{\Omega }}_{\mathrm{m}}$ when calculating ${\sigma }_{\mu }(z)$ increases the probability of finding a residual lensing bias on these parameters greater than $1\sigma$ by 1.5–3 times. Underestimating ${\sigma }_{\mu }(z)$ by using low resolution/small sky-area simulations can also significantly increase the probability of biased results; the probability of a $1\sigma (2\sigma )$ bias in $H_0$ and ${\mathrm{\Omega }}_{\mathrm{m}}$ found from binary neutron star mergers is 54% (19%) in this case. For neutron star mergers, the mean bias on $H_0$ caused by magnification selection effects is $\mathrm{\Delta }{H}_0=-0.1\mathrm{km}{\mathrm{s}}^{-1}{\mathrm{Mpc}}^{-1}$. The spread around this mean bias—determined by assumptions on ${\sigma }_{\mu }(z)$—is $\mathrm{\Delta }{H}_0=\pm 0.25\mathrm{km}{\mathrm{s}}^{-1}{\mathrm{Mpc}}^{-1}$, comparable to the forecasted uncertainty. These effects do not impact merging neutron stars’ utility for addressing the $H_0$ tension, but left uncorrected they limit their use for precision cosmology. For supermassive black hole binaries, the spread of possible biases on $H_0$ is significant, $\mathrm{\Delta }{H}_0=\pm 5\mathrm{km}{\mathrm{s}}^{-1}{\mathrm{Mpc}}^{-1}$, but $\mathcal{O}(200)$ observations are needed to reduce the variance below the bias. To achieve accurate subpercent level precision on cosmological parameters using standard sirens, first much improved knowledge on the form of the magnification distribution and its dependence on cosmology is needed.

The bubbles that nucleated during slow-roll inflation can be supercritical, i.e., their radii are larger than the Hubble horizon of de Sitter spacetime inside the bubble (an inflating baby universe inside it), and thus naturally develop to the supermassive primordial black holes (SMPBHs) with a multipeak mass function. In this paper, we further investigate relevant phenomenology. After slow-roll inflation ended, the bubbles may be not only supercritical, but also subcritical. It is shown that it seems unlikely for the subcritical bubbles to collapse to SMPBHs. Theoretically, however, before they collapsed such bubbles might have a probability of up tunneling to the supercritical ones and thus contribute to SMPBHs. We present a mechanism for the origin of initial clustering of SMPBHs, which can significantly magnify the merger rate of SMPBH binaries and show the possibility that the merging of such SMPBH binaries explains recent NANOGrav signals.

Increasingly precise astrophysical observations of the last decade in combination with intense theoretical studies allow for drawing a conclusion about potential quark matter presence in neutron stars’ interiors. Quark matter may form the neutron star inner core or be immersed in the form of bubbles, or droplets. We consider the second scenario and demonstrate that even a small fraction of quark matter bubbles can lead to a high nonlinearity of the sound wave. Below the bubble resonant frequency the sound speed is lower than the ambient value. At the resonance it sharply grows. The peak is constrained by viscous dissipation. Above the resonance the speed exceeds the pure neutron star matter value. The dispersion equation for the bubbly neutron star compressibility is derived.

A measurement of the diffuse astrophysical neutrino spectrum is presented using IceCube data collected from 2011–2022 (10.3 years). We developed novel detection techniques to search for events with a contained vertex and exiting track induced by muon neutrinos undergoing a charged-current interaction. Searching for these starting track events allows us to not only more effectively reject atmospheric muons but also atmospheric neutrino backgrounds in the southern sky, opening a new window to the sub-100 TeV astrophysical neutrino sky. The event selection is constructed using a dynamic starting track veto and machine learning algorithms. We use this data to measure the astrophysical diffuse flux as a single power law flux (SPL) with a best-fit spectral index of $\gamma =2.58_{-0.09}^{+0.10}$ and per-flavor normalization of ${\varphi }_{\mathrm{per}\text{-flavor}}^{\text{Astro}}=1.68_{-0.22}^{+0.19}\times {10}^{-18}\times {\mathrm{GeV}}^{-1}{\mathrm{cm}}^{-2}{\mathrm{s}}^{-1}{\mathrm{sr}}^{-1}$ (at 100 TeV). The sensitive energy range for this dataset is 3–550 TeV under the SPL assumption. This data was also used to measure the flux under a broken power law, however we did not find any evidence of a low energy cutoff.

The gravitational positivity bound gives quantitative “swampland” constraints on low-energy effective theories inside theories of quantum gravity. We give a comprehensive discussion of this bound for those interested in applications to phenomenological model building. We present a practical recipe for deriving the bound, and discuss subtleties relevant for realistic models. As an illustration, we study the positivity bound on the scattering of the massive gauge bosons in the Higgs/Stückelberg mechanism. Under certain assumptions on gravitational amplitudes at high energy, we obtain a lower bound $m_V\gtrsim {\mathrm{\Lambda }}_{\mathrm{UV}}^2/g{M}_{\mathrm{Pl}}$ on the gauge boson mass $m_V$, where $g$ is the coupling constant of the gauge field, $M_{\mathrm{Pl}}$ is the reduced Planck mass and ${\mathrm{\Lambda }}_{\mathrm{UV}}$ is the ultraviolet cutoff of the effective field theory. This bound can strongly constrain new physics models involving a massive gauge boson. We also discuss how the bound depends on our high-energy assumptions.

In this paper, we introduce and numerically simulate a quantum-field-theoretic phenomenon called the gauge “slingshot” effect and study its production of gravitational waves. The effect occurs when a source, such as a magnetic monopole or a quark, crosses the boundary between the Coulomb and confining phases. The corresponding gauge field of the source, either electric or magnetic, gets confined into a flux tube stretching in the form of a string (cosmic or a QCD type) that attaches the source to the domain wall separating the two phases. The string tension accelerates the source toward the wall as sort of a slingshot. The slingshot phenomenon is also exhibited by various sources of other codimensionality, such as cosmic strings confined by domain walls or vortices confined by $Z_2$ strings. Apart from the field-theoretic value, the slingshot effect has important cosmological implications, as it provides a distinct source for gravitational waves. The effect is expected to be generic in various extensions of the standard model such as grand unification.

The scalar potential of a multi-Higgs model can possess a rich structure of minima and saddle points, which evolves in an intricate way as the parameters change. In the hot early Universe, it could trigger multistep phase transitions, with exotic intermediate phases and peculiar domain wall configurations. Here, we provide a glimpse into this richness with the example of the three-Higgs-doublet model with the symmetry group $\mathrm{\Sigma }(36)$, either exact or softly broken. We present its phase diagram tracking not only the global minimum but all of its extrema. In particular, we reveal parameter space regions in which the deepest saddle point is charge breaking. This naturally leads to phase transitions between neutral vacua which involve expanding and colliding charge-breaking bubble walls. We also comment on opportunities of multistep phase transitions, on charge-breaking intermediate phases, and on phase transitions between different charge-breaking vacua. We illustrate the general discussion with two benchmark models, one of which possesses competing saddle points and allows for emergence of bubbles of the same true vacuum but with bubble walls of different nature. The intriguing cosmological implications of all these possibilities deserve dedicated study.

Recently entanglement suppression was proposed to be one possible origin of emergent symmetries. Here we test this conjecture in the context of heavy meson scatterings. The low-energy interactions of $D^{(*)}{\overline{D}}^{(*)}$ and $D^{(*)}{D}^{(*)}$ are closely related to the hadronic molecular candidates $X(3872)$ and $T_{cc}(3875{)}^{+}$, respectively, and can be described by a nonrelativistic effective Lagrangian manifesting heavy-quark spin symmetry, which includes only constant contact potentials at leading order. We explore entanglement suppression in a tensor-product framework to treat both the isospin and spin degrees of freedom. Using the $X(3872)$ and $T_{cc}(3875{)}^{+}$ as inputs, we find that entanglement suppression indeed leads to an emergent symmetry, namely, a light-quark spin symmetry, and as such the $D^{(*)}{\overline{D}}^{(*)}$ or $D^{(*)}{D}^{(*)}$ interaction strengths for a given total isospin do not depend on the total angular momentum of light (anti)quarks. The $X(3872)$ and $T_{cc}(3875{)}^{+}$ are predicted to have five isoscalar partners and one isoscalar partner, respectively, while the corresponding partner numbers derived solely from heavy-quark spin symmetry are three and one, respectively. The predictions need to be confronted with experimental data and lattice quantum chromodynamics results to further test the entanglement suppression conjecture.

Within the QCD factorization approach, we employ the new results of form factors of $B_s\to \varphi$ and calculate the branching fractions, $CP$ asymmetries (CPAs) and polarization fractions of the decay modes $B_s\to \varphi ({\rho }^0,\omega )$ in both the standard model (SM) and the family nonuniversal $Z^{\prime }$ model. We find that in SM the above observables are relate to two parameters, ${\rho }_H$ and ${\varphi }_H$, which characterize the end-point divergence in the hard spectator-scattering amplitudes. When setting ${\rho }_H=0.5$ and ${\varphi }_H\in [-180,180]°$, the theoretical uncertainties are large. By combining the experimental data, our results can be used to constrain these two parameters. Supposing ${\rho }_H=0$, we study the effects of the $Z^{\prime }$ boson on the concerned observables. With the available branching fraction of $B_s\to \varphi {\rho }^0$, the possible ranges of parameter spaces are obtained. Within the allowed parameter spaces, the branching fraction of $B_s\to \varphi \omega$ can be enlarged remarkably. Furthermore, the new introduced weak phase plays important roles in significantly affecting the CPAs and polarization fractions, which are important observables for probing the effects of NP. If these decay modes were measured in the on-going LHC-b and Belle-II experiments in the future, the peculiar deviation from SM could provide a signal of the family nonuniversal $Z^{\prime }$ model, which can also be used to constrain the mass of $Z^{\prime }$ boson in turn.

With the expected large number of binary neutron star (BNS) observations through gravitational waves (GWs), third-generation GW detectors, Cosmic Explorer (CE) and Einstein Telescope (ET), will be able to constrain the tidal deformability, and hence the equation of state (EOS) of neutron star (NS) with exquisite precision. A subset of the detected BNS systems can retain residual eccentricity in the detector frequency band. We study the systematic errors due to unmodeled eccentricity in the tidal deformability measurement and its implications for NS EOS and redshift measurement via the Love siren method. We find that the systematic errors in the tidal deformability parameter exceed the statistical errors at an eccentricity of $\sim {10}^{-3}$ ($\sim 3\times {10}^{-4}$) at 10 Hz reference GW frequency for CE (ET). We show that these biases on tidal deformability parameter can significantly bias the NS EOS inference. Furthermore, the error on tidal deformability propagates to the source frame NS mass, which in turn biases the redshift inference. For CE, the redshift inference is significantly biased at an eccentricity of $\sim {10}^{-3}$ (at a reference frequency of 10 Hz). We also study the implications of biased tidal deformability in testing the Kerr nature of black holes. Systematic error on the tidal deformability parameter leads to a nonzero value of tidal deformability for binary black holes, indicating a false deviation from the Kerr nature. Finally, we show that including eccentricity in the waveform model increases the statistical errors in tidal deformability measurement by a factor of $\lesssim 2$. Our study, therefore, highlights the importance of using accurate eccentric waveform models for GW parameter inference.

The accretion disk formed after a neutron star merger is an important contributor to the total ejecta from the merger, and hence to the kilonova and the $r$-process yields of each event. Axisymmetric viscous hydrodynamic simulations of these disks can capture thermal mass ejection due to neutrino absorption and in the advective phase—after neutrino cooling has subsided—and are thus likely to provide a lower limit to the total disk ejecta relative to magnetohydrodynamic evolution. Here we present a comparison between two viscous hydrodynamic codes that have been used extensively on this problem over the past decade; ALCAR and FLASH. We choose a representative setup with a black hole at the center, and vary the treatment of viscosity and neutrino transport. We find good overall agreement ($\sim 10\%$ level) in most quantities. The average outflow velocity is sensitive to the treatment of the nuclear binding energy of heavy nuclei, showing a larger variation than other quantities. We postprocess trajectories from both codes with the same nuclear network, and explore the effects of code differences on nucleosynthesis yields, heating rates, and kilonova light curves. For the latter, we also assess the effect of varying the number of tracer particles in reconstructing the spatial abundance distribution for kilonova light curve production.

We discuss the issue of perturbativity in single-field inflationary models with a phase of ultraslow-roll (USR) tailor suited to generate an order-one abundance of primordial black holes (PBHs). More in detail, we impose the condition that loop corrections made up of short-wavelength modes enhanced by the USR dynamics do not alter the tree-level power spectrum of curvature perturbations. In our analysis, the USR phase is preceded and followed by two stages of ordinary slow-roll (SR), and we model the resulting SR/USR/SR dynamics using both instantaneous and smooth transitions. Focusing on scales relevant for cosmic microwave background observations, we find that it is not possible, with these arguments, to rule out the scenario of PBH formation via USR, not even in the limit of instantaneous transition. However, we also find that loop corrections of short modes on the power spectrum of long modes, even though not large enough to violate perturbativity requirements, remain appreciable and, most importantly, are not tamed in realistic realizations of smooth SR/USR/SR transitions. This makes perturbativity a powerful theoretical tool to constrain USR dynamics. We extend the analysis at any scale beyond those relevant for cosmic microwave background observations. We find that loop corrections of short modes remain within the few percent if compared to the tree-level power spectrum. However, we also find one notable exception of phenomenological relevance: we show that the so-called dip in the power spectrum of curvature perturbation is significantly reduced beyond the tree-level computation.

We show that the abundance of primordial black holes, if formed through the collapse of large fluctuations generated during inflation and unless the power spectrum of the curvature perturbation is very peaked, is always dominated by the broadest profile of the compaction function, where the corresponding threshold is $2/5$, even though statistically it is not the most frequent. This result exacerbates the tension when combining the primordial black hole abundance with the signal seen by pulsar timing arrays and originated from gravitational waves induced by the same large primordial perturbations.

In this study, we investigate the role of the nonlinear memory effect in gravitational wave (GW) parameter estimation; particularly, we explore its capability to break the degeneracy between luminosity distance and inclination angle in binary coalescence events. Motivated by the rapid growth in GW detections and the increasing sensitivity of GW observatories enhancing the precision of cosmological and astrophysical measurements is crucial. We propose leveraging the nonlinear memory effect—a subtle, persistent feature in the GW signal resulting from the cumulative impact of emitted gravitational waves—as a novel approach to enhance parameter estimation accuracy. Through a comprehensive series of injection studies, encompassing both reduced and full parameter spaces, we evaluate the effectiveness of nonlinear memory in various scenarios for aligned-spin systems. Our findings demonstrate the significant potential of nonlinear memory in resolving the inclination-distance degeneracy, particularly for events with high signal-to-noise ratios ($>90$) for the current generation of detectors or closer than 1 Gpc in the context of future detector sensitivities such as the planned LIGO ${\mathrm{A}}^{\#}$ upgrade. The results also suggest that excluding nonlinear memory from parameter estimation could introduce significant systematics in future LIGO ${\mathrm{A}}^{\#}$ detections. This observation will hold even greater weight for next-generation detectors, highlighting the importance of including nonlinear memory in GW models for achieving high-accuracy measurements for GW astronomy.